The invention concerns an angularly adjustable drainage foil for paper machines. Concerned here are shallow strips which contact the wire in the machine and normally possess in their front section a scraper type front edge. These front edges serve the removal or stripping of water from the wire. In operation, a small angle of inclination is set between the surface of the wire and the surface of the foil, which creates, when viewed in the direction of travel of the belt, a diverging angle between wire and foil which generates a vacuum on the wire and, depending on the size of the angle, causes a more or less pronounced water drainage.
A system of this general type is known, e.g., from the utility model G 91 05 328. Presented here is a drainage foil whose angle is set such that the support structure of the drainage foil is hinged, on its front edge by means of a joint, to a stable base structure which extends across the machine width, while the other side features pins adapted to engage a slot, said slots extending at a small angle of elevation along a rod which extends through the carrier. The carrier is then raised or lowered on the one side by a longitudinal motion of the rod and through the intermediary of the pins, thereby causing an adjustment of the angle of incidence between wire surface and foil surface. Additional expensive measures are provided here to avoid mechanical backlash. A disadvantage of this arrangement is the high design and production engineering expense, which expresses itself in high manufacturing costs. A further disadvantage is that adjusting the angle causes the height of the edge to change.
The problem underlying the present invention is to provide an angularly adjustable drainage foil for paper machines where a quick and precise setting of the foil angle is possible in the range of zero to several degrees, with great significance being attached to a solution that is simple and in view of manufacturing engineering easy to accomplish, and thus also a low-cost solution. The height of the edge or surface supporting the wire should preferably not change, or change only a little.